This invention relates to toilet flush valve systems of the type through which two different flush volumes of water may be released in order to evacuate a toilet bowl.
Toilet bowl flush systems of the foregoing type enabling the user to select two different quantities of flushing water have already been devised in connection with water conservation programs. However, such prior dual-volume flushing systems usually create certain drawbacks insofar as operational reliability and manufacturing costs are concerned.
According to one known type of dual-volume flushing system, a weighted float is used to sense the water level, and then cause the flap valve to close early, when so required. There is a latching mechanism to control whether or not the float affects the flap valve. The disadvantage of this arrangement is that the mechanism is quite complex. Such dual-volume flushing systems are disclosed, for example, in U.S. Pat. Nos. 4,764,995, 4,620,331, 4,811,432, and 4,455,694.
Another type of dual-volume flushing system is disclosed in U.S. Pat. No. 4,837,867. This system is simple, yet has the disadvantages that the water does not flow freely and with force when the smaller volume is selected. Also, the user must hold the actuator for the duration of the flush when the smaller volume is selected.
Another type of dual-volume flushing system is disclosed in U.S. Pat. No. 4,504,984. This system is complex in that it requires two flap valves and two valve seat openings. Such a system is relatively difficult to install.